Immunogenic epitopes prediction of SP15 protein of Phlebotomus papatasi salivary gland by bioimmunoinformatic

SP15 is one of the most immunogenic proteins of Phlebotomus papatasi saliva, the vector of Leishmania major that drives Th1 response in cutaneous leishmaniasis infection. Here, we tried to predict the immunogenic T-cell epitopes of SP15 using computational prediction for epitope-based vaccine design in future [1]. Online software including SYFPEITHI, RANKPED, NETMHC, and IEDB were used for both HLA class I (HLA-A*0201) and HLA class II (HLA-DRB*10101) prediction. EpiJen and NETCTL were also used for HLA class I prediction. IC50 below 500 for Machine Learning Methods and a score over 20 for SYFPEITHI was used as threshold of prediction [2,3]. Peptides were selected if predicted by at least 3 different algorithms. By evaluating the results, we observed that the epitope KADIRKIMEHCAKKVKKQA (amino acids 61-79) was made up of high scored T-helper epitopes (KADIRKIMEHCAKKV, DIRKIMEHCAKKVKK, IRKIMEHCAKKVKKQ, RKIMEHCAKKVKKQA). The hallmark of this peptide region is a 9-mer core sequence (IMEHCAKKV) that is a strong HLA-A*0201 binder potentially cleaved by proteasome. Two other peptides AIQEYDKTI and YQYYGFVAM were also predicted to be good binders to HLA-A*0201predicted by at least 3 different software. Here we advantaged the potential of computational tools to predict T cell epitopes of SP15. SP15 is a potential vaccine candidate and here we demonstrated that this protein contains peptide regions that can strongly stimulate T cell responses (both CD4 and CD8). It is noteworthy to further evaluate the in vitro and in vivo immunogenicity of this epitope for further peptide vaccine design.

Keywords:

Phlebotomus papatasi , SP15epitope , HLA I/II